fast-reroute per-prefix level-2 all

[sachin30720041]

Hello,

I have the following set up. R1 , R2 and R3 are CSR routers. And running isis.

I have configured 'fast-reroute per-prefix level-2 all' on R1 but I do not see the 'repair path' for 2.2.2.2(R2's loopback) and 3.3.3.3(R3's loopback). What else should I configure so that R1 will have repair path for 2.2.2.2 and 3.3.3.3?

R1#show ip route 3.3.3.3
Routing entry for 3.3.3.3/32
Known via "isis", distance 115, metric 20, type level-2
Redistributing via isis 1
Last update from 100.10.30.3 on GigabitEthernet2, 00:00:55 ago
Routing Descriptor Blocks:
* 100.10.30.3, from 3.3.3.3, 00:00:55 ago, via GigabitEthernet2
Route metric is 20, traffic share count is 1 

                                                 R1

                                        /                \

                                    /                        \

                                 R2-------------R3

R1
-------------------
ipv6 unicast-routing
int gi1
ip address 100.10.20.1 255.255.255.0
ipv6 address 2001:12::1/128
ip router isis 1
ipv6 router isis 1
no sh

int gi2
ip address 100.10.30.1 255.255.255.0
ipv6 address 2001:13::1/128
ip router isis 1
ipv6 router isis 1
no sh

int lo0
ip address 1.1.1.1 255.255.255.255
ipv6 address 1::/128
ip router isis 1
ipv6 router isis 1

router isis 1
metric-style wide
net 49.0001.1111.1111.1111.00
fast-reroute per-prefix level-2 all
exit

R2
-------------------
ipv6 unicast-routing
int gi1
ip address 100.10.20.2 255.255.255.0
ipv6 address 2001:12::2/128
ip router isis 1
ipv6 router isis 1
no sh

int gi3
ip address 100.20.30.2 255.255.255.0
ipv6 address 2001:23::2/128
ip router isis 1
ipv6 router isis 1
no sh

int lo0
ip address 2.2.2.2 255.255.255.255
ipv6 address 2::2/128
ip router isis 1
ipv6 router isis 1
exit

router isis 1
metric-style wide
net 49.0002.2222.2222.2222.00
exit

R3
-------------------
ipv6 unicast-routing

int gi2
ip address 100.10.30.3 255.255.255.0
ipv6 address 2001:13::3/128
ip router isis 1
ipv6 router isis 1
no sh

int gi3
ip address 100.20.30.3 255.255.255.0
ipv6 address 2001:23::3/128
ip router isis 1
ipv6 router isis 1
no sh

int lo0
ip address 3.3.3.3 255.255.255.255
ipv6 address 3::3/128
ip router isis 1
ipv6 router isis 1
exit

router isis 1
metric-style wide
net 49.0003.3333.3333.3333.00
exit

Thanks,

Sachin

[balaji.bandi · Accepted solution]

i would check the config - if they connected back to back (I would re-visit the IP address configured for the p2p IP)

check do you have first ISIS neighbourship before you go next level :

#show isis neighbors

[Harold Ritter · Accepted solution]

Hi @sachin30720041 ,

As per the following document, make sure you configure the isis interfaces as p2p.

• Loop-Free Alternate (LFA) Fast Reroute (FRR) can protect paths that are reachable through an interface only if the interface is a point-to-point interface.

• When a LAN interface is physically connected to a single neighbor, you should configure the LAN interface as a point-to-point interface so that it can be protected through LFA FRR.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_pi/configuration/xe-3s/iri-xe-3s-book/iri-ip-lfa-frr.html

Regards,